Relatively little is known about the transduction process by which sounds and accelerations are converted into electrical signals within the inner ear. We are employing an in vitro preparation from the bullfrog to study the cell biology and electrophysiology of hair cells, the primary receptors of the auditory and vestibular systems. Electrical responses to calibrated mechanical stimuli will be recorded with intracellular microelectrodes. Conductance changes associated with the response will be sought, and the ionic dependence of receptor potentials examined by systematic exchanges of bathing media. The effects of streptomycin and other ototoxic drugs will be examined both physiologically and by freeze-fracture electron microscopy.